Field of the Invention
The present invention relates to flame-retardant, impact-modified polycarbonate (PC) compositions comprising cyclic phosphazenes, which compositions have high heat distortion resistance, very high notched impact strength, excellent flame resistance and high hydrolytic stability, and also to processes for their production, and to the use of cyclic phosphazenes as flame retardants in polycarbonate compositions.
Description of Related Art
EP0728811 A2 discloses polycarbonate/ABS moulding compositions comprising phosphazene as flame retardant. The moulding compositions have good flame retardancy, high impact strength, a high melt volume-flow rate and a high bending modulus.
JP 2000 351893 discloses impact-modified polycarbonate moulding compositions comprising phosphazenes, which compositions are distinguished by good hydrolytic stability, good flame retardancy and stability of the electrical properties.
EP 1 095 099 A1 describes polycarbonate/ABS moulding compositions provided with phosphazenes and phosphorus compounds, which compositions have excellent flame retardancy and very good mechanical properties such as joint line strength or notched impact strength.
EP 1 196 498 A1 describes moulding compositions provided with phosphazenes and based on polycarbonate and graft polymers selected from the group of the silicone, EP(D)M and acrylate rubbers as graft base, which compositions have excellent flame retardancy and very good mechanical properties such as stress cracking resistance or notched impact strength.
EP 1 095 100 A1 describes polycarbonate/ABS moulding compositions comprising phosphazenes and inorganic nanoparticles, which compositions have excellent flame retardancy and very good mechanical properties.
EP 1 095 097 A1 describes polycarbonate/ABS moulding compositions provided with phosphazenes, which compositions have excellent flame retardancy and very good processing properties, wherein the graft polymer is produced by means of mass, solution or mass-suspension polymerisation processes.
US2003/040643 A1 describes a process for the preparation of phenoxyphosphazenes, as well as polycarbonate/ABS moulding compositions comprising these phenoxyphosphazenes. The moulding compositions have good flame retardancy, good flowability, good impact strength and high heat distortion resistance.
In the above-mentioned documents, linear and cyclic phosphazenes are disclosed. In the case of the cyclic phosphazenes, the contents of trimers, tetramers and higher oligomers are not specified, however.
US 2003/092802 A1 discloses phenoxyphosphazenes, as well as their preparation and use in polycarbonate/ABS moulding compositions. The phenoxyphosphazenes are preferably crosslinked, and the moulding compositions are distinguished by good flame retardancy, good impact strength, a high bending modulus and a high melt volume-flow rate. The ABS used is not described more precisely. Moreover, the contents of trimers, tetramers and higher oligomers of the present application are not described in this document.
JP 2004 155802 discloses cyclic phosphazenes and their use in thermoplastic moulding compositions such as polycarbonate and ABS. Polycarbonate/ABS moulding compositions comprising cyclic phosphazenes with precisely defined contents of trimers, tetramers and higher oligomers are not disclosed.
JP 1995 0038462 describes polycarbonate compositions comprising graft polymers, phosphazenes as flame retardants and optionally vinyl copolymers. Specific structures, compositions and amounts of the flame retardant are not mentioned, however.
JP19990176718 describes thermoplastic compositions consisting of aromatic polycarbonate, copolymer of aromatic vinyl monomers and vinyl cyanides, graft polymer of alkyl (meth)acrylates and rubber, and phosphazene as flame retardant, which compositions have good flowability.